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BELL SYSTEM TECHSICAL JOURNAL 



out for the outer boundary of the empty space. The deflecting atoms 

 were atoms of argon, each consisting of eighteen electrons surrounding 

 a nucleus; atoms of oxygen with eight electrons apiece, and atoms 

 of nitrogen with se\en (the latter two kinds of atoms not being dis- 

 criminated in the stud\' of liie data). Rlackett concludi-d that the 



/p ' 



4 



J 



V^:--.. 





5 s 



r 



Fig. 9 



u 



10 



TT 



empt\' space in the argon atom extends out at least to a dislanci- ol 

 10"* cm. from the nucleus in the argon atom, and to a distance ol at 

 least oXlO"'" cm. in the nitrogen and oxygen atoms. 



We now pass to the case of electrons deflected !)>■ atoms. Since the 

 electron is so very much lighter than the ali)ha-parlicle, and yet is 

 half as strongly charged, it will be much more seriously deflected 

 by a nucleus than an al|)ha-particle, aiiiiroaching along the same 

 line with the same speed, would be. This contrast is \-ery strikiiigiv 

 illustrated b>' two results published last summer. Harkins and 

 R\an. photogra[ihing the p.iths of eight\- thousand alph;i-parli(ie> 



